Conventional notebook computers and portable appliances are developed to be more compact in size. As a result, the components found inside notebook computers and portable appliances are closely packed, resulting impeded air circulation. More importantly, notebook computers and portable appliances cannot use axial fans to remove heat from their cases, as found in desktop computers. Therefore, conventional notebook computers and portable appliances generally use a remote heat exchanger to provide a heat-dissipation solution. The heat generated by notebook computers and portable appliances is removed through thermal conduction or forced convection.
FIGS. 1 and 2 show a prior art remote heat exchanger (1) comprising a body (11), an extension (12) extending from the body (11) and a fan (13). With reference to FIG. 3 as well, the body (11) has a cavity (111) therein and the cavity (111) has a single primary opening (112) on left side thereof and a radial fan (13) mounted on a bottom aperture of the body (11). The cool air sucked from the bottom aperture is driven to the primary opening (112). The extension (12) is extended from a right top portion of the body (11). A heat pipe (14) is provided in the remote heat exchanger (1) and is embedded in the extension (12) and the body (11). The extension (12) has a thermal interface (121) on a bottom thereof to transfer heat from an electronic component (31) attached thereto to the heat pipe (14). The thermal interface (121) can be, for example, a thermal grease or a thermal pad used to be applied between two objects to conduct heat from one to the other.
FIG. 3 shows a sectional view of a chassis (2) of a notebook computer or a portable appliance. The primary opening (112) is provided to match an air outlet (22) of the chassis (2), and the fan (13) is provided to match an air inlet (21) of the chassis. The CPU (31) on topside of the circuit board (3) is in contact with the thermal interface (121) of the extension (12). The other major heat generating component (32) (such as North Bridge chip, NB) and heat generating component (33) (such as South Bridge chip, SB) are arranged on the bottom side of the circuit board (3). During operation, the heat generated by the CPU (31) is conducted to the thermal interface (121) of the extension (12) and then conducted to the body (11) through the heat pipe (14). Then, the cool air drawn through the fan (13) blows over the body (11) and carry away the heat in the body (11) and is then ejected out of the air outlet (22) through the primary opening (112). Therefore, the heat generated by the CPU (31) is efficiently removed. As can be seen from above description, the prior art remote heat exchanger (1) uses a heat pipe (14) or a heat spreader to conduct the heat generated by the CPU (31) to a specific location. Moreover, the remote heat exchanger (1) sucks cool air by the radial fan (13) and the cool air flows through the cavity (111) to the primary opening (112). Therefore, the heat is carried by the cool air and ejected out of the notebook computer or portable appliance through the air outlet thereof.
However, the prior art remote heat exchanger (1) has only one primary opening (112) and is used to remove heat from components on one side of the circuit board. Therefore, the prior art remote heat exchanger (1) can only remove heat from the CPU (31) on one side of the circuit board (3) and cannot remove heat from other heat generating component such as component (32) or component (33), found on the other side of the circuit board (3). As a result, the performance and lifetime of the electronic components other than the CPU (31) can be deteriorated due to high temperature.
As can be seen from above description, the notebook computer has limited space for the incorporation of a heat-dissipation device. Once the arrangement of the internal modules and components are determined, it is almost impossible to change the existing arrangement, including the size and the form factor. The redesign job is time consuming and costs a lot. The provision of heat-dissipation device to simultaneously solve the heat-dissipation problem for the components on both sides of the circuit board (3) while keeping the size and form factor is a problem that requires a solution.